Method for transmitting/receiving signals by using TDD scheme in wireless communication system, and communication device for same

ABSTRACT

This method for a communication device to transmit/receive signals by using a TDD scheme in a wireless communication system may comprise the steps of: receiving information related to a guard period (GP) position in a data zone of a particular subframe; receiving downlink data in the data zone of the particular subframe on the basis of the information related to the GP position; and transmitting uplink data in the data zone of the particular subframe on the basis of the information related to the GP position.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the National Phase of PCT International ApplicationNo. PCT/KR2016/007554, filed on Jul. 12, 2016, which claims priorityunder 35 U.S.C. 119(e) to U.S. Provisional Application Nos. 62/257,200,filed on Nov. 18, 2015 and 6/257,745, filed on Nov. 20, 2015, all ofwhich are hereby expressly incorporated by reference into the presentapplication.

TECHNICAL FIELD

The present invention relates to a wireless communication system, andmore particularly, to a method of transmitting and receiving a signalusing a TDD scheme in a wireless communication system and an apparatustherefor.

BACKGROUND ART

3GPP LTE (3rd Generation Partnership Project Long Term Evolution) systemis designed with a frame structure having a TTI (transmission timeinterval) of 1 ms and data requirement latency time for a videoapplication is 10 ms. Yet, with the advent of a new application such asreal-time control and tactile internet, 5G technology in the futurerequires data transmission of lower latency and it is anticipated that5G data requirement latency time is going to be lowered to 1 ms.

However, the legacy frame structure of 1 ms TTI is unable to satisfy the1 ms data requirement latency. 5G aims to provide data latency reducedas much as 10 times compared to the legacy data latency.

Although 5G communication system requires a new frame structure to solvethe abovementioned problem, the new frame structure has not beenproposed yet.

DISCLOSURE OF THE INVENTION Technical Tasks

A technical task of the present invention is to provide a method for acommunication apparatus to transmit and receive a signal using a TDDscheme in a wireless communication system.

Another technical task of the present invention is to provide acommunication apparatus for transmitting and receiving a signal using aTDD scheme in a wireless communication system.

Technical tasks obtainable from the present invention are non-limitedthe above-mentioned technical task. And, other unmentioned technicaltasks can be clearly understood from the following description by thosehaving ordinary skill in the technical field to which the presentinvention pertains.

Technical Solution

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, accordingto one embodiment, a method for transmitting and receiving signals, by acommunication apparatus, using a TDD scheme in a wireless communicationsystem, includes receiving information related to a position of a guardperiod (GP) in a data zone of a specific subframe, receiving downlinkdata in the data zone of the specific subframe based on the informationrelated to the position of the GP, and transmitting uplink data in thedata zone of the specific subframe based on the information related tothe position of the GP. The information related to the position of theGP in the data zone can be received in the specific subframe. Theinformation related to the position of the GP in the data zone can bereceived in a subframe appearing prior to the specific subframe as manyas M number of subframes. The information related to the position of theGP in the data zone can be received via a PCFICH (physical controlformat indicator channel) of the specific subframe. The informationrelated to the position of the GP in the data zone can be received via adownlink control channel of the specific subframe. The downlink data canbe received during a symbol period ranging from a start symbol of thedata zone of the specific subframe to a symbol immediately before asymbol at which the GP is positioned based on the information related tothe position of the GP. The uplink data can be transmitted during asymbol period ranging from a symbol immediately after a symbol at whichthe GP is positioned to a symbol prior to an uplink control zone in thespecific subframe based on the information related to the position ofthe GP.

To further achieve these and other advantages and in accordance with thepurpose of the present invention, according to a different embodiment, acommunication apparatus for transmitting and receiving signals using aTDD scheme in a wireless communication system includes a receiver, atransmitter, and a processor, the processor configured to control thereceiver to receive information related to a position of a GP (guardperiod) in a data zone of a specific subframe and receive downlink datain the data zone of the specific subframe based on the informationrelated to the position of the GP, the processor configured to controlthe transmitter to transmit uplink data in the data zone of the specificsubframe based on the information related to the position of the GP. Theprocessor can control the receiver to receive the information related tothe position of the GP in the data zone of the specific subframe. Theprocessor can control the receiver to receive the information related tothe position of the GP in the data zone in a subframe appearing prior tothe specific subframe as many as M number of subframes. The processorcan control the receiver to receive the information related to theposition of the GP in the data zone via a PCFICH (physical controlformat indicator channel) of the specific subframe. The processor cancontrol the receiver to receive the information related to the positionof the GP in the data zone via a downlink control channel of thespecific subframe. The processor can control the receiver to receive thedownlink data during a symbol period ranging from a start symbol of thedata zone of the specific subframe to a symbol immediately before asymbol at which the GP is positioned based on the information related tothe position of the GP. The processor can control the transmitter totransmit the uplink data during a symbol period ranging from a symbolimmediately after a symbol at which the GP is positioned to a symbolprior to an uplink control zone in the specific subframe based on theinformation related to the position of the GP.

Advantageous Effects

According to a frame structure provided by the present invention, it isable to achieve low latency (i.e., OTA (w/ initiation)<1 ms)corresponding to 5G service requirement and provide DL/UL flexibilitycapable of efficiently supporting asymmetry of DL/UL traffic as much aspossible.

According to one embodiment, it is able to efficiently performcommunication by securing DL/UL flexibility as much as possibleaccording to a proposed TDD frame structure.

Effects obtainable from the present invention may be non-limited by theabove mentioned effect. And, other unmentioned effects can be clearlyunderstood from the following description by those having ordinary skillin the technical field to which the present invention pertains.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention.

FIG. 1 is a block diagram for configurations of a base station 105 and auser equipment 110 in a wireless communication system 100;

FIG. 2 is a diagram for explaining correlation between IMT 2020 coreperformance requirement for 5G and 5G performance requirement perservice scenario;

FIG. 3 is a diagram for LTE/LTE-A frame structure;

FIG. 4 is a diagram for an example of FDD/TDD frame structure inLTE/LTE-A system;

FIGS. 5A and 5B are diagrams for an example of a self-contained subframestructure;

FIG. 6 is a diagram for a HARQ procedure when a UL resource of a datazone is immediately allocated;

FIG. 7 is a diagram for a HARQ procedure when a UL resource of a datazone is not immediately allocated;

FIG. 8 is a diagram for a new frame structure according to a proposal1-1 of the present invention;

FIG. 9 is a diagram for explaining a case that DL transmission timing isoverlapped with UL transmission timing;

FIG. 10 is a diagram illustrating an example that a DL data symbolboundary is not matched with a UL data symbol boundary in a data zone ina base station;

FIG. 11 is a diagram illustrating an example of an RF structure of atransceiver of a base station;

FIG. 12 is a diagram illustrating an example of a frame structuretime-frequency resource on a TDD carrier;

FIG. 13 is a diagram illustrating an example of a frame structuretime-frequency resource on a FDD carrier;

FIG. 14 is a diagram illustrating an example of a frame structureconfigurable in TDD.

BEST MODE Mode for Invention

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. In the following detailed description of the inventionincludes details to help the full understanding of the presentinvention. Yet, it is apparent to those skilled in the art that thepresent invention can be implemented without these details. Forinstance, although the following descriptions are made in detail on theassumption that a mobile communication system includes 3GPP LTE system,the following descriptions are applicable to other random mobilecommunication systems in a manner of excluding unique features of the3GPP LTE.

Occasionally, to prevent the present invention from getting vaguer,structures and/or devices known to the public are skipped or can berepresented as block diagrams centering on the core functions of thestructures and/or devices. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.

Besides, in the following description, assume that a terminal is acommon name of such a mobile or fixed user stage apparatus as a userequipment (UE), a mobile station (MS), an advanced mobile station (AMS)and the like. And, assume that a base station (BS) is a common name ofsuch a random node of a network stage communicating with a terminal as aNode B (NB), an eNode B (base station), an access point (AP) and thelike. Although the present specification is described based on IEEE802.16m system, contents of the present invention may be applicable tovarious kinds of other communication systems.

In a mobile communication system, a user equipment is able to receiveinformation in downlink and is able to transmit information in uplink aswell. Information transmitted or received by the user equipment node mayinclude various kinds of data and control information. In accordancewith types and usages of the information transmitted or received by theuser equipment, various physical channels may exist.

The following descriptions are usable for various wireless accesssystems including CDMA (code division multiple access), FDMA (frequencydivision multiple access), TDMA (time division multiple access), OFDMA(orthogonal frequency division multiple access), SC-FDMA (single carrierfrequency division multiple access) and the like. CDMA can beimplemented by such a radio technology as UTRA (universal terrestrialradio access), CDMA 2000 and the like. TDMA can be implemented with sucha radio technology as GSM/GPRS/EDGE (Global System for Mobilecommunications)/General Packet Radio Service/Enhanced Data Rates for GSMEvolution). OFDMA can be implemented with such a radio technology asIEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, E-UTRA (EvolvedUTRA), etc. UTRA is a part of UMTS (Universal Mobile TelecommunicationsSystem). 3GPP (3rd Generation Partnership Project) LTE (long termevolution) is a part of E-UMTS (Evolved UMTS) that uses E-UTRA. The 3GPPLTE employs OFDMA in DL and SC-FDMA in UL. And, LTE-A (LTE-Advanced) isan evolved version of 3GPP LTE.

Moreover, in the following description, specific terminologies areprovided to help the understanding of the present invention. And, theuse of the specific terminology can be modified into another form withinthe scope of the technical idea of the present invention.

In case of performing wireless transmission between a base station and aUE, a transmission to the UE from the base station is commonly referredto as a DL transmission and a transmission to the base station from theUE is commonly referred to as a UL transmission. A scheme of determininga radio resource between the DL transmission and the UL transmission isdefined as duplex. When a frequency band is divided into a DLtransmission band and a UL transmission band and transmission andreception are performed in both directions, it is referred to asfrequency division duplex (FDD).

FIG. 1 is a block diagram for configurations of a base station 105 and auser equipment 110 in a wireless communication system 100.

Although one base station 105 and one user equipment 110 (D2D userequipment included) are shown in the drawing to schematically representa wireless communication system 100, the wireless communication system100 may include at least one base station and/or at least one userequipment.

Referring to FIG. 1, a base station 105 may include a transmitted (Tx)data processor 115, a symbol modulator 120, a transmitter 125, atransceiving antenna 130, a processor 180, a memory 185, a receiver 190,a symbol demodulator 195 and a received data processor 197. And, a userequipment 110 may include a transmitted (Tx) data processor 165, asymbol modulator 170, a transmitter 175, a transceiving antenna 135, aprocessor 155, a memory 160, a receiver 140, a symbol demodulator 155and a received data processor 150. Although the base station/userequipment 105/110 includes one antenna 130/135 in the drawing, each ofthe base station 105 and the user equipment 110 includes a plurality ofantennas. Therefore, each of the base station 105 and the user equipment110 of the present invention supports an MIMO (multiple input multipleoutput) system. And, the base station 105 according to the presentinvention may support both SU-MIMO (single user-MIMO) and MU-MIMO (multiuser-MIMO) systems.

In downlink, the transmission data processor 115 receives traffic data,codes the received traffic data by formatting the received traffic data,interleaves the coded traffic data, modulates (or symbol maps) theinterleaved data, and then provides modulated symbols (data symbols).The symbol modulator 120 provides a stream of symbols by receiving andprocessing the data symbols and pilot symbols.

The symbol modulator 120 multiplexes the data and pilot symbols togetherand then transmits the multiplexed symbols to the transmitter 125. Indoing so, each of the transmitted symbols may include the data symbol,the pilot symbol or a signal value of zero. In each symbol duration,pilot symbols may be contiguously transmitted. In doing so, the pilotsymbols may include symbols of frequency division multiplexing (FDM),orthogonal frequency division multiplexing (OFDM), or code divisionmultiplexing (CDM).

The transmitter 125 receives the stream of the symbols, converts thereceived stream to at least one or more analog signals, additionallyadjusts the analog signals (e.g., amplification, filtering, frequencyupconverting), and then generates a downlink signal suitable for atransmission on a radio channel. Subsequently, the downlink signal istransmitted to the user equipment via the antenna 130.

In the configuration of the user equipment 110, the receiving antenna135 receives the downlink signal from the base station and then providesthe received signal to the receiver 140. The receiver 140 adjusts thereceived signal (e.g., filtering, amplification and frequencydownconverting), digitizes the adjusted signal, and then obtainssamples. The symbol demodulator 145 demodulates the received pilotsymbols and then provides them to the processor 155 for channelestimation.

The symbol demodulator 145 receives a frequency response estimated valuefor downlink from the processor 155, performs data demodulation on thereceived data symbols, obtains data symbol estimated values (i.e.,estimated values of the transmitted data symbols), and then provides thedata symbols estimated values to the received (Rx) data processor 150.The received data processor 150 reconstructs the transmitted trafficdata by performing demodulation (i.e., symbol demapping, deinterleavingand decoding) on the data symbol estimated values.

The processing by the symbol demodulator 145 and the processing by thereceived data processor 150 are complementary to the processing by thesymbol modulator 120 and the processing by the transmission dataprocessor 115 in the base station 105, respectively.

In the user equipment 110 in uplink, the transmission data processor 165processes the traffic data and then provides data symbols. The symbolmodulator 170 receives the data symbols, multiplexes the received datasymbols, performs modulation on the multiplexed symbols, and thenprovides a stream of the symbols to the transmitter 175. The transmitter175 receives the stream of the symbols, processes the received stream,and generates an uplink signal. This uplink signal is then transmittedto the base station 105 via the antenna 135.

In the base station 105, the uplink signal is received from the userequipment 110 via the antenna 130. The receiver 190 processes thereceived uplink signal and then obtains samples. Subsequently, thesymbol demodulator 195 processes the samples and then provides pilotsymbols received in uplink and a data symbol estimated value. Thereceived data processor 197 processes the data symbol estimated valueand then reconstructs the traffic data transmitted from the userequipment 110.

The processor 155/180 of the user equipment/base station 110/105 directsoperations (e.g., control, adjustment, management, etc.) of the userequipment/base station 110/105. The processor 155/180 may be connectedto the memory unit 160/185 configured to store program codes and data.The memory 160/185 is connected to the processor 155/180 to storeoperating systems, applications and general files.

The processor 155/180 may be called one of a controller, amicrocontroller, a microprocessor, a microcomputer and the like. And,the processor 155/180 may be implemented using hardware, firmware,software and/or any combinations thereof. In the implementation byhardware, the processor 155/180 may be provided with such a deviceconfigured to implement the present invention as ASICs (applicationspecific integrated circuits), DSPs (digital signal processors), DSPDs(digital signal processing devices), PLDs (programmable logic devices),FPGAs (field programmable gate arrays), and the like.

Meanwhile, in case of implementing the embodiments of the presentinvention using firmware or software, the firmware or software may beconfigured to include modules, procedures, and/or functions forperforming the above-explained functions or operations of the presentinvention. And, the firmware or software configured to implement thepresent invention is loaded in the processor 155/180 or saved in thememory 160/185 to be driven by the processor 155/180.

Layers of a radio protocol between a user equipment/base station and awireless communication system (network) may be classified into 1st layerL1, 2nd layer L2 and 3rd layer L3 based on 3 lower layers of OSI (opensystem interconnection) model well known to communication systems. Aphysical layer belongs to the 1st layer and provides an informationtransfer service via a physical channel. RRC (radio resource control)layer belongs to the 3rd layer and provides control radio resourcedbetween UE and network. A user equipment and a base station may be ableto exchange RRC messages with each other through a wirelesscommunication network and RRC layers.

In the present specification, although the processor 155/180 of the userequipment/base station performs an operation of processing signals anddata except a function for the user equipment/base station 110/105 toreceive or transmit a signal, for clarity, the processors 155 and 180will not be mentioned in the following description specifically. In thefollowing description, the processor 155/180 can be regarded asperforming a series of operations such as a data processing and the likeexcept a function of receiving or transmitting a signal without beingspecially mentioned.

The present invention proposes new and various frame structures for a5^(th) generation (5G) communication system. In a next generation 5Gsystem, scenarios can be classified into Enhanced Mobile BroadBand(eMBB), Ultra-reliable Machine-Type Communications (uMTC), MassiveMachine-Type Communications (mMTC), and the like. The eMBB correspondsto a next generation mobile communication scenario having such acharacteristic as high spectrum efficiency, high user experienced datarate, high peak data rate, and the like, the uMTC corresponds to a nextgeneration mobile communication scenario having such a characteristic asultra-reliable, ultra-low latency, ultra-high availability, and the like(e.g., V2X, Emergency Service, Remote Control), and the mMTC correspondsto a next generation mobile communication scenario having such acharacteristic as low cost, low energy, short packet, and massiveconnectivity (e.g., IoT).

FIG. 2 is a diagram for explaining correlation between IMT 2020 coreperformance requirement for 5G and 5G performance requirement perservice scenario.

FIG. 2 illustrates correlation between core performance requirement for5G proposed by IMT 2020 and 5G performance requirement per servicescenario.

In particular, uMTC service has very high restriction on Over The Air(OTA) Latency Requirement and requires high mobility and highreliability (OTA Latency: <1 ms, Mobility: >500 km/h, BLER: <10⁻⁶).

FIG. 3 is a diagram for LTE/LTE-A frame structure.

FIG. 3 shows a basic concept of a frame structure of LTE/LTE-A. Oneframe corresponds to 10 ms and includes 10 1-ms subframes. One subframeincludes 2 0.5-ms slots and one slot includes 7 OFDM (OrthogonalFrequency Division Multiplexing) symbols. One resource block (RB) isdefined by 12 subcarriers each of which has 15 kHz space and 7 OFDMsymbols. A base station delivers a primary synchronization signal (PSS)and a secondary synchronization signal (SSS) for synchronization aphysical broadcast channel (PBCH) for system information in a centerfrequency (6RBs). In this case, it may have a difference in the framestructure and positions of the signal and the channel depending on anormal/extended CP (cyclic prefix) and TDD (Time Division Duplex)/FDD(Frequency Division Duplex).

FIG. 4 is a diagram for an example of FDD/TDD frame structure inLTE/LTE-A system.

Referring to FIG. 4, in case of a FDD frame structure, a downlinkfrequency band is distinguished from an uplink frequency band. In caseof a TDD frame structure, a downlink region is distinguished from anuplink region in a subframe unit in the same band.

FIGS. 5A and 5B are diagram for an example of a self-contained subframestructure.

FIGS. 5A and 5B illustrate a self-contained subframe structure which isproposed to satisfy a low-latency requirement among 5G performancerequirements. A TDD-based self-contained subframe structure has aresource section for downlink, a resource section for uplink (e.g., adownlink control channel and an uplink control channel), a guard period(GP) for solving an interference issue between downlink and uplink, anda resource section for data transmission in a single subframe.

FIG. 5A shows an example of a self-contained subframe structure. Asubframe is configured in an order of a resource section for downlink, aresource section for uplink, and a resource section for data and a GPexists between the resource sections. In FIG. 5A, a downlink resourcesection represented as DL may correspond to a resource section for adownlink control channel and an uplink resource section represented asUL may correspond to a resource section for an uplink control channel.

FIG. 5B shows a different example of a self-contained subframestructure. A subframe is configured in an order of a resource sectionfor downlink, a resource section for data, and a resource section foruplink and a GP exists prior to the resource section for uplink only. InFIG. 5B, a downlink resource section represented as DL may correspond toa resource section for a downlink control channel and an uplink resourcesection represented as UL may correspond to a resource section for anuplink control channel.

The next generation 5G system is considering V2X targeting ultra-lowlatency, eMBB service targeting emergency service, machine control, anddata speed, and the like. Hence, it is necessary to design a framestructure capable of supporting low latency (OTA <1 ms) and high degreeof freedom of DL/UL data. And, it is necessary to design acommonality-based single frame structure which is not necessary to beredesigned in TDD or FDD operation scheme.

In order to provide the low latency and the degree of freedom of DL/ULdata configuration in the next generation 5G system, the presentinvention proposes a method of configuring a new frame structure and acontrol zone. In the present specification, such a term as a zoneindicates a resource. Such a terms as a region, a channel, and the likecan be used together with the zone in the same meaning.

Proposal 1: New Frame Structure (Adaptive/Self-Contained FrameStructure) for 5G Systems

It is difficult to satisfy a requirement of OTA <1 ms in a currentLTE/LTE-A TDD frame structure. And, although TDD scheme provides variousTDD DL/UL configurations to efficiently support asymmetry (DL traffic>ULtraffic) of DL/UL data amount, it causes a complex procedure for HARQ(hybrid automatic repeat request) ACK/NACK time depending on a TDD DL/ULconfiguration. In order to solve the problem, as shown in FIGS. 5A and5B, self-contained frame structures provide an opportunity fortransmitting ACK/NACK in every subframe by simultaneously configuring aDL control zone (or, a DL control channel, a DL control region) and anUL control zone in a single subframe.

FIG. 6 is a diagram for a HARQ procedure when a UL resource of a datazone is immediately allocated.

When a data zone is always guaranteed as an UL data zone or a DL datazone (or, DL data region) based on the subframe structure shown in FIG.5B, it may be able to perform a HARQ procedure within 5 subframesbetween OTA (w/initiation), i.e., UL buffer arrival, and final ACK/NACKreception.

FIG. 6 illustrates an example that HARQ ACK is received within 5subframes. A corresponding procedure is described in the following.Subframe #1: if a data to be transmitted in UL is generated and a bufferarrival event is triggered, a UE transmits a scheduling request (SR)using an UL control zone. A subframe #2 corresponds to time forperforming UL scheduling. A subframe #3 corresponds to a DL controlzone. The UE receives a UL grant and prepares data to be transmitted inthe subframe #3. The UE transmits UL data via a data zone in a subframe#4. A subframe #5 corresponds to time for a base station to receive dataand perform Rx processing. The UE receives ACK via a DL control channelin a subframe #6.

According to the abovementioned procedure, from the timing at which thebuffer arrival event occurred to the timing at which the ACK isreceived, it is able to see that the procedure occurs within 5subframes. Hence, if TTI is configured by 0.2 ms, ‘OTA (w/ initiation)<1ms’ is satisfied. However, since a data zone is restricted to a UL datazone or a DL data zone in a single subframe, if DL (or UL) trafficconsiderably occurs, as shown in FIG. 7, it is apparent that a case offailing to transmit DL (or UL) traffic occurs.

FIG. 7 is a diagram for a HARQ procedure when a UL resource of a datazone is not immediately allocated.

As shown in FIG. 7, if it fails to perform scheduling on UL data due toDL traffic for other UEs in a fourth subframe form the left side,latency as much as 1 subframe occurs and it is unable to satisfy ‘OTA(w/ initiation)<1 ms’. Moreover, if it is necessary to transmit more DLtraffic, the latency is going to be extended. In particular, in order toachieve not only asymmetry of DL/UL traffic amount but also low latency,it is necessary to guarantee the degree of freedom of DL/UL traffic asmuch as possible in a data zone.

The present invention proposes a new frame structure capable ofsatisfying low latency and DL/UL data flexibility on the basis of asingle carrier.

Proposal 1-1

FIG. 8 is a diagram for a new frame structure according to a proposal1-1 of the present invention.

As shown in FIG. 8, a subframe is mainly divided into a DL control zone(or DL control channel), a GP, a data zone (data region or datachannel), and a UL control zone (or UL control channel) on a singlecarrier. A frame structure shown in FIG. 8 corresponds to a framestructure which is configured under the assumption that a base stationoperates in a full duplex radio (FDR) scheme. Meanwhile, the framestructure shown in FIG. 8 may correspond to a frame structure allocatedby a base station for a single UE. For example, if the frame structureshown in FIG. 8 corresponds to a frame structure allocated by a basestation for a single UE, a DL data zone, a UL data zone, and a UL datazone are allocated to the UE according to a band in frequency domaindirection in a first subframe shown in FIG. 8. In this case, the UEreceives DL data from the base station on a band represented by DL andtransmits UL data to the base station on a band represented by UL. Inparticular, the frame structure shown in FIG. 8 may correspond to aframe structure allocated to the UE under the assumption that the UE isable to operate in the FDR as well.

In FIG. 8, the DL data zone and the UL data zone, which are allocatedaccording to a band in a subframe, can be differently configuredaccording to a subframe. For example, referring to FIG. 8, a DL datazone, a UL data zone, and a UL data zone can be allocated according to aband in frequency domain direction in a second subframe.

As shown in FIG. 8, a DL control zone is located at the first (start) ofa subframe in time domain, a data zone (a zone represented by DL, UL) islocated right after the DL control zone, and a UL control zone is lastlylocated after the data zone. In this case, the data zone can be used asa DL data or a UL data in frequency domain without any restriction. And,a GP is located between the DL control zone and the data zone when databelonging to a corresponding band corresponds to UL. On the contrary,when data corresponds to DL, a GP is located between the data zone andthe UL control zone.

As shown in FIG. 8, a UL transmission occasion and a DL transmissionoccasion exist at the same time in a data zone in every subframe. Inparticular, it is able to prevent additional latency due to therestriction of a legacy data zone restricted to DL or UL. If a length ofa subframe is configured to be equal to or less than 0.2 ms, it is ableto achieve ‘OTA (w/ initiation)<1 ms’.

Moreover, a base station may have more efficiency via DL/UL flexibilityof the data zone in the aspect of utilizing DL/UL data resource comparedto a legacy self-contained TDD frame structure. Hence, the framestructure shown in FIG. 8 is able to get rid of inefficiency due to theasymmetry of DL/UL traffic and achieve low latency.

Embodiment of Proposal 1-1

Embodiment for a method of achieving low latency and an operating methodwhen DL data transmission timing is overlapped with UL data transmissiontiming are described in the following.

FIG. 9 is a diagram for explaining a case that DL transmission timing isoverlapped with UL transmission timing.

As shown in FIG. 9, when a DL buffer arrival event and a DL bufferarrival event respectively occur, one of the two buffer arrival eventshas no choice but to be delayed in a legacy frame structure. In FIG. 9,it is assumed that 2 traffics (DL traffic and UL traffic) areoverlapped. If more traffic occurs at the same time, more latency mayoccur.

On the other hand, referring to a frame structure shown in FIG. 9, sincea DL data zone and a UL data zone are allocated within a subframe, it isable to transmit DL data and UL data at the same time and simultaneoustransmission is also supported while minimum latency is maintained. Theframe structure shown in FIG. 9 has a merit in that a gain increasesaccording to the increase of traffic.

Proposal 1-2

A DL control zone and a UL control zone can be configured by 1 to Nnumber of symbols. A GP is configured by an integer multiple of asymbol. More specifically, a length of a GP can be configured by aninteger multiple of a unit symbol allocated to a data zone.

In general, a length of a GP is designed by a round trip time (RTT) andRF switching time (from DL to UL/from UL to DL). Hence, the length ofthe GP can be determined by a method of minimizing overhead inconsideration of RTT and RF switching time overhead (e.g., aself-contained frame structure).

If the frame structure shown in FIG. 8 corresponds to a frame structureallocated by a base station for a plurality of UEs, the base stationoperates in a full duplex scheme that performs UL/DL data transmissionand reception at the same time in a data zone. On the contrary, The UEsoperate in a half-duplex scheme that performs either transmission orreception only. Hence, it is necessary for the base station to transmitDL data and receive UL data at the same time. In this case, if GPs areconfigured according to a legacy method, as shown in FIG. 10, it isapparent that interference occurs due to the mismatch between symbolboundaries.

FIG. 10 is a diagram illustrating an example that a DL data symbolboundary is not matched with a UL data symbol boundary in a data zone ina base station.

A base station receives data transmitted in DL within in-band. Hence, ifa level of the mismatch is less than a CP length, it is able to receiveUL data without interference on an ideal channel via orthogonality ofOFDM. Yet, as shown in FIG. 10, a GP makes a symbol boundary between ULdata and DL data to be mismatched. Hence, as shown in FIG. 8, it may beable to cancel the interference by configuring a GP length of a datazone by a symbol length.

In particular, the GP length of the data zone is configured to satisfyequation 1 in the following all the time by making the GP length to bean integer multiple of a length of a unit symbol that constructs thedata zone.Length of data zone÷Number of symbols in data zone=Length of singlesymbol=T_cp+T_u=GP length÷k  [Equation 1]

In this case, k is a natural number, T_cp corresponds to a CP length,and T_u corresponds to a length of a data part in a symbol. Inparticular, a length of a GP becomes an integer multiple of a length ofa unit symbol that constructs a data zone.

And, a DL control zone and a UL control zone can be configured by Nnumber of symbols without being restricted to a single symbol.

The frame structure shown in FIG. 10 requires a transceiver configuredto perform DL and UL (i.e., transmission and reception) at the same timein a DL zone. A structure of the transceiver can be configured asfollows.

FIG. 11 is a diagram illustrating an example of an RF structure of atransceiver of a base station.

FIG. 11 illustrates configurations of devices for performingtransmission and reception at the same time in a single carrier. Firstof all, in order to reduce power leakage that a signal transmitted by abase station is entering a receiving end, a signal is attenuated using acirculator. In addition, it may be able to additionally suppress aself-interference signal via an analog SIC device.

The frame structure proposed in the proposal 1 has the characteristicthat transmission occasion of DL/UL traffic of FDD is always guaranteedin a legacy system. The frame structure can also efficiently use aresource according to asymmetry of DL/UL traffic of TDD.

In the following, a frame structure of a base station and a UE operatingin a TDD or FDD mode is proposed.

Proposal 2-1

In a TDD carrier, a subframe is mainly divided into a DL control zone, aGP, a data zone, and a UL control zone. The DL control zone is locatedat the first of the subframe, the data zone is located right after theDL control zone, and the UL control zone is lastly located after thedata zone. In this case, the data zone can be used as a DL data or a ULdata in the subframe. And, a GP is located between the DL control zoneand the data zone when data belonging to a corresponding bandcorresponds to UL. On the contrary, when data corresponds to DL data, aGP is located between the data zone and the UL control zone. The DLcontrol zone and the UL control zone can be configured by 1 to N numberof symbols. A GP is configured by an integer multiple of a symbol.

FIG. 12 is a diagram illustrating an example of a frame structuretime-frequency resource on a TDD carrier.

As shown in FIG. 12, a data zone of every subframe is allocated as a ULdata zone or a DL data zone. Hence DL/UL flexibility is lowered comparedto the frame structure of the proposal 1. Yet, since the DL control zoneand the UL control zone are still located within a single subframe, ‘OTA(w/ initiation)<1 ms’ can be achieved by a scheduler. Moreover, since itis able to utilize the data zone as a DL data zone or a UL data zone bythe scheduler, it is apparent that the frame structure is more DL/ULflexible compared to the legacy LTE TDD.

A length of a GP is configured by a multiple of a symbol length. Thismakes numerology (subcarrier spacing, CP length, symbol length, numberof symbols in a TTI) used in TDD to be identically used in a FDD framestructure. In particular, it is a design method for providingcommonality as much as possible in the TDD and FDD frame structures. Asa result, it may be able to maintain a lot of common parts in a basebandoperation.

For example, when a GP is designed by a length of half symbol withoutbeing maintained by the length of one symbol, if the same TTI isapplied, the number of symbols or a CP length varies in TDD and FDD andit breaks unity in terms of an implementation device. As a result, itmay implement TDD and FDD, respectively. On the contrary, if a GP lengthis maintained by a multiple of a symbol length, since it is able tocommonly use a CP, a symbol length, and the like, it may have anadvantage that a commonly used implementation part increases.

Proposal 2-2

FIG. 13 is a diagram illustrating an example of a frame structuretime-frequency resource on a FDD carrier.

In FIG. 13, a subframe is mainly divided into a control zone and a datazone on a FDD carrier. In case of DL, the control zone is located at thefirst of the subframe and the data zone is located after the controlzone. In case of UL, a UL control zone is located at the first of thesubframe and the data zone is located after the UL control zone.

FIG. 13 illustrates a frame structure that a GP is utilized as a dataand a control zone is located at the first part of a subframe in alegacy TDD frame structure. As mentioned in the foregoing description,commonality is maximized by maintaining a common part with the legacyTDD frame structure as much as possible.

As mentioned in the foregoing description, the frame structure accordingto the proposal provided by the present invention can achieve lowlatency (i.e., OTA (w/ initiation)<1 ms) corresponding to 5G servicerequirement and provide DL/UL flexibility capable of efficientlysupporting asymmetry of DL/UL traffic as much as possible.

In the foregoing description, the new frame structure has been proposedto achieve low latency (i.e., OTA (w/ initiation)<1 ms) corresponding to5G service requirement and provide DL/UL flexibility capable ofefficiently supporting asymmetry of DL/UL traffic as much as possible.In the proposal 1, DL/UL flexibility is provided via a structure capableof transmitting DL and UL at the same time by dividing a data zoneaccording to a frequency band. On the other hand, according to the TDDframe structure proposed in the proposal 2-1, a data zone of a subframeis determined as either UL or DL by a scheduler of a base station.Hence, the degree of freedom of DL/UL is basically lower than that ofthe proposal 1.

Hence, it is necessary to have a method of improving flexibility oftraffic amount of DL and UL in TDD structure. In particular, it is ableto more enhance frequency efficiency in such a service having a verysmall packet size and a sporadic characteristic as mMTC.

In the following, a new frame structure for enhancing DL/UL flexibilityin the TDD frame structure mentioned earlier in the proposal 2-1 isproposed.

Proposal 3: Configurable New Frame Structure for Unpaired Spectrum (TDD)in 5G Systems

The new TDD frame structure proposed in the proposal 2-1 provides lowerlatency and DL/UL flexibility of a data zone compared to a legacy LTETDD structure. However, due to the characteristic of TDD, it may use aresource in one direction (i.e., UL or DL) only at specific time. Thus,a data zone of a subframe in new TDD frame structure used as DL or UL.As a result, if UL data traffic occurs, the entire data zone should beused for UL. In this case, if an amount of the traffic occurred in UL isinsignificant, the waste of the data zone in a corresponding subframebecome significant.

In particular, since a bandwidth of a wideband (˜100 MHz) is consideredfor 5G service, inefficiency of a resource is significant. Moreover, ifterminals sporadically generate a very small packet size in an mMTCservice, efficiency of a resource is more degraded. As a solution, itmay configure a TTI to be shorter. However, it makes GP overhead to beincreased as much as twice and increases overhead of DL control as well.Hence, it is necessary to have a method of more enhancing DL/ULflexibility in the current frame structure. The present inventionproposes a new frame structure for enhancing DL/UL data flexibility in aTDD frame structure and signaling therefor.

Proposal 3-1

In a carrier which operates on TDD scheme, a subframe is mainlyconfigured in an order of a DL control zone, a DL data zone, a GP, a ULdata zone, and a UL control zone. In this case, a size of the DL datazone and a size of the UL data zone are determined according to aposition of the GP. The GP may be positioned at any position in the datazone.

FIG. 14 is a diagram illustrating an example of a frame structureconfigurable in TDD.

Referring to FIG. 4, a second subframe (subframe 1) includes a DL datazone (represented as DL in a subframe 1) of a size of 5 symbols, a GP,and a UL data zone (represented as UL in the subframe 1) of a size of 5symbols. And, a third subframe (subframe 2) includes a DL data zone of asize of 8 symbols, a GP, and a UL data zone of a size of 2 symbols. Thisconfiguration method can be appropriately controlled by a scheduler of abase station according to traffic amount. If the GP is positioned at thefirst symbol or the last symbol of the data zone, the whole of the datazone can be used as either UL or DL.

Since a size of a DL data zone is big in a subframe 0, a GP ispositioned after the DL data zone and a UL control zone is positionedafter the GP. In this case, UE processing time for transmitting HARQACK/NACK in the UL control zone of the subframe 0 in response to DLreception in the subframe 0 is insufficient. Hence, a UE can transmitthe HARQ ACK/NACK in response to DL reception in the subframe 0 in a ULcontrol zone of a subframe 1 corresponding to a next subframe.

Meanwhile, since a size of a DL data zone of the subframe 1 is smallerthan that of the subframe 0, UE processing time is secured. Hence, a UEcan transmit HARQ ACK/NACK in the UL control zone of the subframe 1 inresponse to DL reception in the subframe 1. Similar to the data zonerespectively set to the subframe 0 and the subframe 1, a size of the DLdata zone and a size of the UL data zone can be flexibly changedaccording to a subframe based on the DL/UL flexibility property. Byassigning number of symbols smaller than symbols assigned to DL datazone of the subframe 0 are assigned to the DL data zone of the subframe1, a UE can immediately transmit HARQ ACK/NACK in the subframe 1 inresponse to DL reception in the subframe 1.

Proposal 3-2: base station can signal location information of GP to UEin every subframe via DL control zone

According to the legacy LTE system, TDD configuration is signaledthrough system information block type 1 (SIB1). In case of the SIB1,transmission is performed in every 80 ms. This configuration method isnot sufficient enough for dynamically controlling DL/UL traffic amountin various services of 5G. Hence, the present invention enhancesflexibility of DL/UL data in a manner that a base station informs a UEof information in a DL control zone of every subframe. In particular, itmay be able to enhance DL/UL flexibility by changing a legacycell-specific configuration method with a subframe-specificconfiguration method.

When the base station informs the UE of information, the information mayinclude information related to a position of a GP in a data zone of aspecific subframe (a corresponding subframe or a subframe appearingafter M number of subframes).

When the number of symbols of a data zone corresponds to N in total, theinformation related to the position of the GP in the data zone isconfigured by a size as much as the number of bits rounded from log 2N.And, it may be able to reduce the number of bits by reducing subdivisionof the GP position. For example, when a data zone is configured by 10symbols in total, a position of a GP can be indicated by 4 bits. If thedata zone is configured by 1, 4, 7, or 10 symbols only, the GP positioncan be indicated by 2 bits. A method of signaling the informationrelated to the position of the GP in the data zone may be divided intotwo methods described in the following.

1. In case of indicating a GP position of a corresponding subframe

Method 1: A base station may inform a UE of location information of a GPvia a DL control channel (e.g., PDCCH, EPDCCH) in a DL control zone. Inthis case, the location information of the GP may be indicated to allUEs to which a resource is allocated in a corresponding subframe via acommon search space. For decoding, the location information of the GPmay be transmitted in a manner of being masked with an ID (e.g.,SI-RNTI) known to all UEs.

Method 2: A base station may inform a UE of location information of a GPvia an independent channel (e.g., PCFICH). Unlike the method 1performing blind decoding, the method 2 can increase robustness ofdetection and reduce calculation complexity of a UE by determining MCSand an RE position.

If the UE knows the location information of the GP, the UE can know thata UL data zone is positioned before and after the GP in the DL datazone. In particular, if the UE receives the location information of theGP, the UE is able to receive DL data during a period ranging from asymbol appearing after the DL control zone to a symbol immediatelybefore a symbol at which the GP is positioned. The UE can transmit ULdata during a period ranging from a symbol appearing after the GP to asymbol immediately before the last symbol.

2. In case of indicating GP position after next M frames

Method 1: A base station may inform a UE of location information of a GPvia a DL control information channel (e.g., PDCCH, EPDCCH) in a DLcontrol zone. In this case, the location information of the GP can beindicated to all UEs to which a resource is allocated after next Msubframes via a common search space. For decoding, the locationinformation of the GP can be transmitted in a manner of being maskedwith an ID (e.g., SI-RNTI) known to all UEs.

Method 2: A base station may inform a UE of location information of a GPafter next M subframes via an independent channel (e.g., PCFICH). Unlikethe method 1 performing blind decoding, the method 2 can increaserobustness of detection and reduce calculation complexity of a UE bydetermining a determined MCS and an RE position.

A GP position can be subframe-specifically configured and it is notnecessary to UE-specifically configure the GP position.

The proposed frame structure can provide more enhanced DL/UL flexibilityusing a configurable frame structure and a signaling method.

The above-described embodiments correspond to combinations of elementsand features of the present invention in prescribed forms. And, therespective elements or features may be considered as selective unlessthey are explicitly mentioned. Each of the elements or features can beimplemented in a form failing to be combined with other elements orfeatures. Moreover, it is able to implement an embodiment of the presentinvention by combining elements and/or features together in part. Asequence of operations explained for each embodiment of the presentinvention can be modified. Some configurations or features of oneembodiment can be included in another embodiment or can be substitutedfor corresponding configurations or features of another embodiment. And,it is apparently understandable that an embodiment is configured bycombining claims failing to have relation of explicit citation in theappended claims together or can be included as new claims by amendmentafter filing an application.

Those skilled in the art will appreciate that the present invention maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent invention. The above embodiments are therefore to be construedin all aspects as illustrative and not restrictive. The scope of theinvention should be determined by the appended claims and their legalequivalents, not by the above description, and all changes coming withinthe meaning and equivalency range of the appended claims are intended tobe embraced therein.

INDUSTRIAL APPLICABILITY

A method of transmitting and receiving a signal using a TDD scheme in awireless communication system and an apparatus therefor can be appliedto various wireless communication systems including 3GPP LTE/LTE-A, 5Gsystem, and the like.

What is claimed is:
 1. A method for transmitting and receiving signals,by a communication apparatus, based on a TDD scheme using a plurality ofsubframes in a wireless communication system, the method comprising:receiving information related to a position of a guard period (GP) in adata zone of a specific subframe, wherein each of the plurality ofsubframes includes a downlink control zone, a data zone and an uplinkcontrol zone in sequence, each of the plurality of subframes is one ofamong a first subframe, a second subframe and a third subframe, a firstdata zone of the first subframe includes a first GP and a first uplinkdata zone in sequence, a second data zone of the second subframeincludes a first downlink data zone and a second GP in sequence, and athird data zone of the third subframe includes a second downlink datazone, a third GP and a second uplink data zone in sequence; receivingdownlink data in the data zone of the specific subframe based on theinformation related to the position of the GP, wherein the specificsubframe is one of among the second subframe and the third subframe, andthe data zone is a corresponding one of among the first downlink datazone and the second downlink data zone; and transmitting uplink data inthe data zone of the specific subframe based on the information relatedto the position of the GP, wherein the specific subframe is one of amongthe first subframe and the second subframe, and the data zone is acorresponding one of among the first uplink data zone and the seconduplink data zone.
 2. The method of claim 1, wherein the informationrelated to the position of the GP in the data zone is received in thespecific subframe.
 3. The method of claim 2, wherein the informationrelated to the position of the GP in the data zone is received via aphysical control format indicator channel (PCFICH) of the specificsubframe.
 4. The method of claim 2, wherein the information related tothe position of the GP in the data zone is received via a downlinkcontrol channel of the specific subframe.
 5. The method of claim 1,wherein the infoiination related to the position of the GP in the datazone is received in a subframe appearing prior to the specific subframeas many as M number of subframes.
 6. The method of claim 1, wherein thespecific subframe is the first subframe based on the position of the GPbeing located at a starting symbol of the data zone, and the specificsubframe is the second subframe based on the position of the GP being alast symbol of the data zone.
 7. The method of claim 6, wherein thespecific subframe is the third subframe based on the position of the GPbeing located at remaining symbols of the data zone, and the remainingsymbols are located between the starting symbol and the last symbol. 8.The method of claim 1, wherein a time interval of the GP is same as atime interval of one symbol.
 9. The method of claim 1, wherein a timeinterval of one subframe is equal to or less than 0.2 ms.
 10. Acommunication apparatus for transmitting and receiving signals based ona TDD scheme using a plurality of subframes in a wireless communicationsystem, the communication apparatus comprising: a receiver; atransmitter; and a processor configured to control: the receiver toreceive information related to a position of a guard period (GP) in adata zone of a specific subframe, wherein each of the plurality ofsubframes includes a downlink control zone, a data zone and an uplinkcontrol zone in sequence, each of the plurality of subframes is one ofamong a first subframe, a second subframe and a third subframe, a firstdata zone of the first subframe includes a first GP and a first uplinkdata zone in sequence, a second data zone of the second subframeincludes a first downlink data zone and a second GP in sequence, and athird data zone of the third subframe includes a second downlink datazone, a third GP and a second uplink data zone in sequence; the receiverto receive downlink data in the data zone of the specific subframe basedon the information related to the position of the GP, wherein thespecific subframe is one of among the second subframe and the thirdsubframe, and the data zone is a corresponding one of among the firstdownlink data zone and the second downlink data zone; and thetransmitter to transmit uplink data in the data zone of the specificsubframe based on the information related to the position of the GP,wherein the specific subframe is one of among the first subframe and thesecond subframe, and the data zone is a corresponding one of among thefirst uplink data zone and the second uplink data zone.
 11. Thecommunication apparatus of claim 10, wherein the processor is configuredto control the receiver to receive the information related to theposition of the GP in the data zone of the specific subframe.
 12. Thecommunication apparatus of claim 11, wherein the processor is configuredto control the receiver to receive the information related to theposition of the GP in the data zone via a physical control formatindicator channel (PCFICH) of the specific subframe.
 13. Thecommunication apparatus of claim 11, wherein the processor is configuredto control the receiver to receive the information related to theposition of the GP in the data zone via a downlink control channel ofthe specific subframe.
 14. The communication apparatus of claim 10,wherein the processor is configured to control the receiver to receivethe information related to the position of the GP in the data zone in asubframe appearing prior to the specific subframe as many as M number ofsubframes.
 15. The communication apparatus of claim 10, wherein thespecific subframe is the first subframe based on the position of the GPbeing located at a starting symbol of the data zone, and the specificsubframe is the second subframe based on the position of the GP being alast symbol of the data zone.
 16. The communication apparatus of claim10, wherein the specific subframe is the third subframe based on theposition of the GP being located at remaining symbols of the data zone,and the remaining symbols are located between the starting symbol andthe last symbol.
 17. The communication apparatus of claim 10, wherein atime interval of the GP is same as a time interval of one symbol. 18.The communication apparatus of claim 10, wherein a time interval of onesubframe is equal to or less than 0.2 ms.